St. John's weather in September
September in St. John's: sweltering, rainy, with clean air — an excellent time to visit.
#9 of 12 months in St. John's · #275 of 604 destinations to visit in September · comfort 82/100 (tier A)
Updated June 2026 · climate normals from ERA5 reanalysis
St. John's climate normals — September
| Daytime high | 29°C / 85°F | 🔥 sweltering |
|---|---|---|
| Nighttime low | 27°C / 80°F | |
| Feels like (high) | 34°C / 93°F | |
| Rainfall | 102 mm / 4 in | 🌧 rainy |
| Rainy days | 18 days | |
| Humidity | 78% | 💦 very humid |
| Dew point | 24°C / 75°F | |
| Sunshine | 11 h/day | |
| Daylight | 12.2 h | |
| Wind | 25 km/h / 16 mph | |
| Air quality (US AQI) | 37 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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St. John's in September — FAQ
- Is September a good time to visit St. John's?
- September in St. John's: sweltering, rainy, with clean air — an excellent time to visit. It ranks #9 of 12 months for St. John's on SeasonMap's comfort score (82/100).
- What is the weather like in St. John's in September?
- In September, St. John's averages a daily high of 29.3°C and a low of 26.8°C, with about 102 mm of rain over roughly 18.4 rainy days.
- What is the air quality in St. John's in September?
- St. John's has a mean US Air Quality Index of about 37 in September.